This invention relates to a chain thrower mechanism for gear change operations in a bicycle. In bicycles a gear change can be effected by dislocating the bicycle chain between chain sprockets of different teeth number and different size, which sprockets are connected for common rotation either with a pedalling shaft of the respective bicycle or with a driver member of the rearwheel of the respective bicycle.
Such chain thrower mechanisms generally comprise two terminal members, namely a frame side terminal member adapted to be fastened on a bicycle frame, and a thrower side terminal member adapted to be assembled with a chain thrower unit, and further comprise at least one connecting member hingedly connected with both said terminal members for guiding said thrower side terminal member along a predetermined path with respect to said frame side terminal member. This chain thrower unit is adapted for engagement with a bicycle chain and for dislocating this bicycle chain between at least two chain sprockets in response to movement of the thrower side terminal member along said predetermined path.
In most cases the chain thrower mechanism comprises two connecting members which form together with the terminal members an articulated parallelogram arrangement.